schema:     DNS-SCHEMA
ref:        dn42.domain
key:        domain     required   single    primary  schema
key:        nserver    required   multiple  > [domain name] [ip addr]
key:        status     required   single    > {EVALPEND,CONNECT} [timestamp]
key:        descr      optional   single
key:        mnt-by     required   multiple  lookup=dn42.mntner
key:        admin-c    optional   multiple  lookup=dn42.person,dn42.role
key:        tech-c     optional   multiple  lookup=dn42.person,dn42.role
key:        org        optional   multiple  lookup=dn42.organisation
key:        country    optional   deprecate single
key:        remarks    optional   multiple
mnt-by:     XUU-MNT
mnt-by:     HEXA-MNT